When large quantities of concrete are to be mixed, for example for the production of concrete blocks or tiles, it is necessary to use a very dry mix and this has associated with it a number of difficult practical problems. Firstly the mix tends to cake or "pack" on the beaters or blades of the mixer, and the mixing efficiency rapidly reduces as concrete builds up on the mixing surfaces.
It is already known that one of the most time consuming and dangerous jobs is the cleaning of the mixing surfaces, and heretofore use has been made of physically large batch mixers which are subject to the abovementioned disability, and which require cleaning, usually twice a day. This is a hazardous operation and some accidents have occurred. The cost of batch mixers is very high, and the energy consumption is also very high.
We have discovered that certain types of continuous mixers are capable of large throughputs with relatively small power inputs, are relatively small dimensionally, and are of low cost. For example, the reader may refer to the invention the subject of our U.S. patent application No. 626,699 dated July 2nd, 1984, wherein the use of a lug belt co-operating with a part loop surface of a base belt for concrete mixing resulted in a considerable improvement in concrete mixing, in throughput and in cost.
The main object of this invention is to provide a continuous mixer wherein the cleaning requirement is less than with the batch type mixer which is presently used in production factories, and wherein there is also an improvement in concrete mixing, in throughput and in cost, and wherein cleaning is facilitated.